EL CAJON  Utility crews worked Friday to replace eight poles that fell over along Mollison Avenue Thursday afternoon, cutting off power, cable and phone service to about 1,500 people.

Service was restored to all customers by 4:30 p.m., San Diego Gas & Electric Co. spokeswoman Amber Albrecht said.

The poles along the west side of Mollison began to topple about 5 p.m. Thursday, with five landing on the ground and three leaning precariously, said Monica Zech, spokeswoman for Heartland Fire & Rescue. One pole fell onto a traffic signal at Lexington Avenue.

No one was injured and no vehicles were damaged.

Two blocks of Mollison were closed between Main Street and Washington Avenue while SDG&E, AT&T and Cox Cable crews began repairs.

Northbound lanes of Mollison were opened between Main Street and Washington Avenue shortly before 6 p.m. Friday, Zech said, and one southbound lane was reopened around midnight.

Two poles that held cable lines are still being fixed, and AT&T crews may be working on them until as late as 11 p.m. Friday. The southbound lanes will remain closed until that work is done.

Utility workers are still trying to determine what caused the poles to fall, Zech said.